Hydraulic dredge production sustanining control



Nov- 6, 1963 a. c. FONNESBECK 3,111,778

HYDRAULIC DREDGE PRODUCTION SUSTAINING CONTROL Filed Jan. 6, 1961 5 Sheets-Sheet 1 INVENTOR.

gym a Pam/5.585%

A TI'OE/VEV Nov. 26, 1963 B. c. FONNESBECK 3,111,773

HYDRAULIC DREDGE PRODUCTION SUSTAINING CONTROL Filed Jan". 6, 1961 s Sheets-Sheet 2 INVENTOR.

- 5)?0/7 C. FO/Y/YFSBFCK BY M w M A TTOR/Y E Y Nov. 26, 1963 B. c. FONNESBECK ,778

HYDRAULIC DREDGE PRODUCTION SUSTAINING CONTROL Filed Jan. 6. 1961 s Sheets-Sheet s INVENTOR. 5)!50 C FU/Y/YESBECK BY 1 ATTORNEY United States Patent 3,111,778 HYDRAULIC DREDGE PRDDUCTHUN SUSTAHNHNG CUNTROL Byron C. Fonnesheck, 6161 McKee, South Eurnahy, British Columbia, fianada Filed Fan. 6, 1961, Ser. No. 81,085 9 Claims. (Ci. 375S) The present invention pertains to a production sustaining control for a suction dredge. This application is a continuation-in-part of my prior abandoned application Serial No. 635,722, filed January 23, 1957, for Suction Dredge Release Valve System.

A hydraulic dredge used for excavating the bottom of a body of water includes a pump and a dredging suction line through which a mixture of dirt and water is drawn by the pump into the pump intake. Such dirt may be in the form of sand or clay or gravel or a mixture of such materials. When sand or clay is being dredged, chunks of packed sand or clay may be drawn into the dredging suction pipe, or marine growth in clumps may enter the dredging suction line, and in either case stones of considerable size may be drawn into the line, which may obstruct the line and reduce the rate of excavation of solid material. Screens may be used to cover the suction end of the dredging suction line, but such screens are not desirable because they tend to be plugged.

To the extent that the suction dredging line of the pump is clogged, the effectiveness of the pump is decreased and the dredging production rate is reduced correspondingly. Consequently, a supplemental water supply bypass suction line is provided to supply water to the intake of the pump by being connected to the dredging suction line at a location adjacent to the pump, thus bypassing the intake end portion of the dredging suction line, and control valve mechanism for such supplemental water supply bypass suction line is operated automatically so that the pumping efilciency and discharge pressure of the pump can be maintained for preserving a substantial suction force on the dredging suction line to clear it.

It is a principal object of the present invention to provide actuating mechanism for the control valve of a supplemental water supply bypass suction line for a dredging pump intake wihch will regulate the opening of the valve in varying degrees corresponding to the degree of reduction in pressure in the pump discharge line which, in turn, is related to the extent to which the dredging suction line of the pump is obstructed. By this expedient, sufficient supplemental water is supplied to the pump intake through the supplemental water supply bypass suction line to preserve the pumping effectiveness of the pump. The pump continues to apply its suction effect principally to the dredging suction line to clear such line while maintaining as great a flow of material through such suction line as possible to sustain the production of the dredge. If no supplemental water were supplied to the pump intake, the plugging would increase because of the reduction of suction developed by the pump which normally would occur as a result of the inadequate water supply. On the other hand, if most of the water required to maintain effective operation of the pump were admitted through a supplemental water supply bypass suction line, the suction applied to the dredging suction line would be com paratively small.

Specifically, it is an object to vary the elfective size of the passage through a supplemental water supply bypass suction line control valve automatically and progressively in response to fluctuations in the discharge pressure of the pump. When an obstruction occurs in the dredging suction line the bypass suction line control valve will be opened only to such a degree as to admit sufiicient water through the supplemental water supply bypass suc- 3,111,778 Patented Nov. 26, 1963 tion line to restore the pumps discharge pressure to approximately its previous value. If the dredging suction line of the pump should be obstructed to a greater degree, the bypass control valve will be opened wider. As the obstruction is cleared progressively during such continued operation of the pump so that the discharge pressure of the pump increases, the bypass control valve will be closed to a degree sufficient to reduce the pump discharge pressure again approximately to the desired selected value.

For accomplishing these objects, the apparatus of the present invention includes pressure-sensing mechanism in communication with the discharge conduit of the pump which operates bypass control valve actuating mechanism connected to alter the position of a valve controlling flow to the suction side of the pump through a supplemental water supply bypass suction line connected in parallel with the dredging suction line of the pump. The control mechanism includes a follow-up device which tends to stabilize the control valve in a newly adjusted position and prevents or reduces overcontrol of the controlling mechanism. By progressive or incremental operation of the bypass control valve, in response to small increases v or decreases in the discharge pressure of the pump, the pump can be kept operating at its maximum efficiency and the dredging suction line kept flowing at its greatest capacity possible for the degree of obstruction accumulated in the dredging suction pipe from time to time. Movement of the valve will be regulated in the opening or closing direction corresponding to a decrease or increase in pressure in the discharge line of the pump substantially in direct proportion to the change in such discharge pressure.

FIGURE 1 is a diagrammatic view of a dredge installation having a bypass control valve according to the invention, and FIGURE 2 is a detail sectional view, taken on line 2-2 in FIGURE 1.

FIGURE 3 is an enlarged diagrammatic view with parts broken away, showing components of the operating mechanism.

FIGURE 4 is a diagrammatic view corresponding to FIGURE 3 of modified valve-operating mechanism which can be employed in the apparatus shown in FIGURE 1 as an alternate to the mechanism of FIGURE 3, parts being broken away.

As shown in FIGURE 1, the dredging apparatus to which the present invention can be applied may be mounted on a scow or barge 10. The principal component of the dredging apparatus is the power driven pump 11 which may be of the centrifugal type having the dredging suction pipe 12 connected to its intake. This dredging suction line includes a flexible section enabling its lower end to be depressed to the bottom of the body of water to be dredged and to be moved from side to side. The water and material dredged by the pump is discharged from the pump through a pipe 13 connected to the pump outlet.

A supplemental water supply suction pipe 14 is connected to the dredging suction pipe 12 at a location adjacent to the pump 11 bypassing the suction end portion of the dredging suction line and extends into the same body of water as the pipe 12. Flow of water through this bypass pipe is controlled by valve mechanism 15 including a butterfly valve 16 mounted on a cross shaft 17. On one end of this cross shaft is secured a control lever 18, projecting substantially equal distances in opposite directions from the shaft.

In a suitable housing or frame 19 is mounted an actuator valve unit Ztl, shown best in FIGURE 3, which includes a cylinder 21 through which extends a valve rod 22 carrying spaced valves 23 and 24 slidably received within the cylinder. Suitable valve rod centering mechanism may include compression springs 25 in the cylinder and reacting respectively between the opposite ends of the cylinder and abutnients on the valve rod. Such springs function to center the valve rod and the valves longitudinally within the cylinder when the valve rod is not subjected to a lengthwise shifting force.

Pipe 26 for supplying compressed air is connected to the central portion of the cylinder 21. Flow through such pipe is controlled by hand valve 27. This pipe is connected to the cylinder inlet 28, preferably located at the center of the cylinder so that it is always between the valves 23 and 24, irrespective of the position of valve rod 22 longitudinally of the cylinder. At each side of the inlet port 28 are exhaust ports to which the exhaust pipes 29 and are connected, respectively. The distance between these exhaust ports and the inlet port 28 should be approximately equal to the spacing between valves 23 and 24 on valve rod 22. At least the stroke of the valve rod should be such that neither valve can move into registry with and block the fluid supply port 28 or either of the exhaust ports to which pipes 29 and 30 are connected.

Located equal distances at opposite sides of the inlet port 28 to the cylinder 21 are ports 31 and 32 to which pipes 33 and 34, respectively, are connected. These pipes lead to the opposite ends of the actuator cylinder unit.

The opposite ends of the cylinder 21 carry solenoids 35 and 36, respectively, which can act on the valve rod 22 as an armature to shift it lengthwise in one direction or the other for the purpose of shifting valves 23 and 24 relative to the inlet port 28 and the outlet ports 3-1 and 32 of the cylinder. When the solenoid 35 is energized, the valve rod and valves will be shifted to the left as seen in FIGURE 3 to locate valve 23 between the outlet port 31 and the exhaust connection 29 and valve 24 between the inlet port 28 and the outlet port 32.

As a result, as shown in FIGURE 3, the fluid supply pipe 26 will be in communication with the outlet pipe 33 through the space within cylinder 21 between valves 23 and 24, while the outlet pipe 34 will be in communication for venting or return of fluid through the exhaust pipe 30. Conversely, when the solenoid 36 is energized, the valve rod 22 and the valves 23 and 24 will be shifted from their positions shown in FIGURE 3 to the right until valve 23 is located between the inlet port 28 and the outlet port 31, while valve 24 will be located to the right of outlet port 32 so as to block communication between outlet pipe 34 and exhaust pipe 30. With the par-ts in this position, fluid under pressure will be supplied from inlet pipe 26 to pipe 34 while fluid may flow out of pipe 33 through the portion of the cylinder 21 to the left of valve 23 for discharge through the exhaust conduit 29.

When both solenoids 3'5 and 36 are deenergized, the springs 25, reacting from the ends of cylinder 21, respectively, against the abutments on the valve rod 22, will move such rod and the valves 23 and 24 to a central position. If the spacing of the valves along the valve rod is the same as the spacing between the outlet ports 31 and 32, these outlet ports will be blocked by their respective valves when the valve rod is centered so that fluid will be sealed in the opposite ends of the actuator cylinder 37 because it can neither be admitted to nor be discharged from such cylinder through the pipes 33 and 34.

The fluid piston-and-cylinder actuator has a cylinder 37 through which a piston rod extends coaxially. Piston is secured on this rod and fits snugly within the cylinder so that it will be moved to the right as seen in FIGURE 3 when fluid under pressure is admitted to the left end of the cylinder through pipe 33 and the right end of the cylinder is relieved of pressure by way of the connecting pipe 34 and the exhaust pipe 30. Conversely, the piston and, consequently, the piston rod 39 will be moved toward the left as seen in FIGURE 3 when the valves 23 and 24 are shifted to the right so that the fluid under pressure will be supplied from conduit 26 through pipe 34 to the right end of cylinder 37 and the portion of the cylinder at the left side of the piston is in communication with the exhaust pipe 29 through pipe 33. The speed of movement of the piston and piston rod effected by fluid under pressure supplied from pipe 26 can be regulated, not only by the valve 27, but by the valves 38 located in the lines 33 and 34. These may be needle valves, if desired, so as to enable the flow of fluid under pressure through pipes 33 and 34 to be regulated very accurately.

Piston rod 39 is of a length such that its opposite end portions extend through and beyond the opposite ends of cylinder 37 and the opposite end portions 41 of this rod carry suitable couplings '42 to which control valve actuating lines 43 are connected. The lines 43 pass over suitable guide pulleys 44 and their ends remote from the cylinder 37 have connectors 45 which secure such line ends, respectively, to opposite ends of the lever 13 mounted on the shaft 17 of butterfly valve 16. These lines should be of a length and an arrangement such that butterfly valve 16 will be in partially opened position, such as approximately half way open, when piston 40 is located approximately centrally within the cylinder 37. As the piston is moved to the left, as seen in FIGURE 3, therefore, it will effect movement of the butterfly valve 16 toward closed position. Conversely, as the actuator piston 40 is reciprocated into a position approaching the right end of cylinder 37, butterfly valve 16 will have been swung so as to approach its extreme open position.

In order to stabilize bypass control valve 16 in any particular desired position as long as a given degree of clogging exists in the suction dredging pipe 12, follow-up mechanism is provided which will effect restoration of the valve rod 22 and valves 23 and 24 to their central position within cylinder 21 until a further change occurs in pressure in the pump discharge line 13. Such follow-up mechanism includes a lever arm 46 having one end mounted by pivot 47 and its opposite end received in the guideway '48 so as to restrict movement of such lever to swinging about its pivot in a plane perpendicular to the axis of such pivot. The central portion of such lever is engaged by a roller 49 rotatably mounted on an end portion 41 of the piston rod 39 by an arm 50 secured to such piston rod end. The distance between the axis of piston rod 39 and the portion of the periphery of roller 49 farthest from the piston rod is somewhat less than the distance between the piston rod axis and the adjacent side of lever arm 46, at the location of its pivot 47. As the piston rod moves to the left, as seen in FIGURE 3, therefore, the lever arm 46 bearing on the roller 49 will swing downward to maintain contact with the roller. Movement of the piston rod to the right, as seen in this figure, on the contrary, will cause roller 49 to bear against the lever arm in a manner to swing it about pivot 4-7 in a counterclockwise direction toward parallelism to the axis of piston rod 39. Such swinging of the lever arm actuates the follow-up mechanism for the valves 23 and 24.

The actuator mechanism further includes a slide 51 engaged in guides or Ways 52 for movement in a plane perpendicular to the axis of lever pivot 47 and in a direction transversely of lever arm 46. On this slide of rod 53 is mounted in cantilever fashion, located so that its free end engages the side of lever arm 46 opposite that engaged by roller 49. This rod is guided for linear movement by a guide 55. The rod and slide assembly is urged toward the lever arm by tension spring 56 connected between the guide and the slide to maintain the free end of the rod 53 in engagement with the lever arm 45.

On the slide 51 are mounted switches 57 and 58 spaced lengthwise of the slide. These switches are connected in circuit with the valve-operating solenoids 36 and 35, respectively. A common wire 59 connects one terminal of each of these switches to one terminal of a power source 59', the other terminal of which is grounded. The other terminal of switch 58 is connected by wire 61 to one terminal of solenoid 35, and the other terminal of such solenoid is grounded by wire 62 to complete a cir cuit to the power source Sh. Similarly, the other terminal of switch 57 is connected to one terminal of solenoid 36 by wire 63 and the other terminal of such solenoid is connected to the ground wire 64 for completion of the circuit from that solenoid to the power source 59.

Switches 57 and 58 are of the normally open type, so that when there is no pressure upon arm 65 of switch 57 or arm 66 of switch 58 these switches are both in the open position. As shown best in FTGURE 3, these switch arms are located on adjacent sides of switches 57 and 58 and project from such switches in generally parallel relationship and are spaced apart a short distance. Such switch arms extend transversely of the direction of movement of the slide 51. Swinging of such a switch arm toward its switch housing will effect closing of the switch to complete a circuit from the power source to the solenoid corresponding to such switch.

Pressure-sensing mechanism for effecting actuation of switch arms 65 and 66 is housed in a casing 79 mounted by a suitable support 71 on a pressure-sensing device 72. Within this pressure-sensing device is a diaphragm 76 movable in response to a change in pressure in the outlet of centrifugal pump 11. This diaphragm is engaged with a rod 79 slidably mounted in casing 749 and normally urged lengthwise toward the diaphragm by the compression spring 8%) reacting between the casing and abutment 31 secured on the rod 79.

A bent rod or band has a short end 82 engaged with the abutment 83. on rod 79, while the longer end portion 83 of the band has its free end located between the switch arms 65 and 66. The bend of this band or rod is engaged with the pin 34 constituting a fulcrum for the band so that it forms a lever. As the pressure on the left side of diaphragm 76 is reduced spring 36 will move rod 79 and its abutment 81 to the left, so that the short end 82 of the band will be tilted toward the left to raise the free end of the longer portion 83 into engagement with the switch arm 66. Conversely, if the pressure on the left side of the diaphragm 76 increases, rod "79 will be forced to the right in opposition to the force of spring 80, so that the abutment 81 will move the free end of the short band end 32 to the right. The longer band end 83 will be depressed by such swinging of the lever so that its free end engages the other switch arm 65 as shown in FIGURE 1.

The pressure-sensing device 72 of the pressure-responsive mechanism is connected by a conduit 86 to the discharge pipe 13 of the pump Ill, as shown in FIGURE 1, and a pressure gauge 87 may be connected to this conduit for reference purposes. A valve 88 may be included in this conduit which can be adjusted to vary the sensitivity of the response of pressure-sensing device 72 to changes in pressure in the pump discharge pipe 13.

When the pump it is operating normally and the dredging suction pipe 12 is clear of obstruction, it is preferred that the control valve 16 for the supplemental water bypass suction pipe 14 will be closed or nearly closed, as shown in FIGURE 1. Under these circumstances piston 4'!) will be adjacent to the left end of the cylinder 37 of the valve actuator as seen in FIGURE 1. The longer band end 83 of the pressure-responsive mechanism will be pressed downward against the switch arm 65 of the switch 57 so that the solenoid 36 is energized for holding the valve stem 22 and valves 2-3 and 24 at the right end of cylinder 21. Compressed air from pipe 26 will thus be supplied to outlet pipe 34 leading to the right end of the actuator cylinder 37 so as to hold the piston at the left for maintaining valve 16 in its farthest closed position. The various parts continue to occupy these positions as long as the pumping operation maintains unobstructed flow through the dredging suction line 12.

If the dredging suction line should become clogged to a greater or lesser extent, the impact or dynamic pressure in the pump discharge line 13 sensed by the pressuresensing device 72 will drop. The resulting decrease in pressure on diaphragm 7 6 pressing the rod 79 to the right against the action of spring St) will thus be relieved and the spring will press the short band end 82 to the left so as to swing the band about the fulcrum 84 and raise the longer band end d3 out of contact with the switch arm 65 and into contact with the switch arm 66, as shown in FIGURE 3. Such shifting of the band end thus effects deenergization of solenoid 36 by opening of switch 65 and energization of solenoid 35 by closing of switch 66.

Such reversal of solenoid energization effects shifting of valve rod 22 and valves 23 and 24 from the right of cylinder 21 to the left positions shown in FIGURE 3. instead of compresesd air being supplied to the right end of actuator cylinder 37 to hold piston 40 to the left end of this cylinder, therefore, compressed air is supplied through outlet pipe 33 from supply pipe 26 to the left end of actuator cylinder 37 while the right end of this cylinder is vented through pipe 34 and exhaust pipe 30. The piston 4%) will therefore be pressed toward the right and will move with it piston rod 359 and control valve actuating lines 43 for swinging control lever 18 to move valve 16 toward open posiiton. Such movement of the piston rod end &1 also, of course, will shift to the right, as seen in FIGURES 1 and 3, arm 56 carried by it. The engagement of such arm with lever arm 46 will swing such lever arm upward for sliding rod 53 and switches 57 and 5S upward until arm 66 of switch 58 is moved out of engagement with the longer band portion 83.

As soon as the switch 58 is thus moved upward far enough so that its switch arm 66 is withdrawn from contact with the band arm 83, this switch will open and deenergize solenoid 35. The centering means for valve rod 22 shown as springs 25 will then shift such valve rod and valves 23 and 24 to the right until the valves are in regis-tery with ports 31 and 32, respectively, to close outlet pipes 33 and 3d. The piston 4% may continue to move slightly to the right in cylinder 37 until the air pressure on opposite sides of it is equal zed, but such travel will not be sufficient to cause arm 50 to shift switch 57 upwards so that its switch arm 65 engages the band portion 33 to close switch 57. All the parts will then remain in this adjusted position until the dynamic or impact pressure in pump discharge pipe 13 changes.

The partial opening of valve 16 thus accomplished will enable water to be drawn through bypass pipe 14- into the dredging suction line 12 in addition to the flow through the dredging suction line so as to maintain the operating efficiency and suction of pump ill. Such maintenance of pump suction will tend to remove the obstruction from the dredging suction pipe which caused the reduction in pump outlet pressure that initiated the control operation described. If the dredging suction line is operating in an adverse situation, however, the clogging of the dredging suction pipe may actually increase before it is reduced. If the clogging is further increased, the pressure in the pump discharge line 13 again will drop so that the diaphragm 76 of the pressure-sensing device 72 will be moved farther to the left by spring hi and the band 32, 83 will be swung to raise the longer end 83 so that it will again contact switch arm 66 and close switch 58. The resulting energization of solenoid 35 will cause the valve rod 22 and valves 23 and 24 again to shift to the left as shown in FIGURE 3 so as to eifeot a further incremental movement of actuator piston 49 to the right. Such piston movement will produce a further increment-al opening movement of bypass control valve 16 and the further upward movement of rod 53 and switches 57 and 58 until switch arm 66 again is withdrawn from band end 83.

Again, the control valve 16 and other parts of the apparatus will remain in this newly adjusted position until the dynamic or impact pressure in the pump discharge line 13 changes further to an extent sufficient to cause the band arm 83 to engage one or the other of switch arms 65 and so for closing the corresponding switch. if the clogging of the suction dredging lhie 12 should become still worse, the band arm will again close switch 66 to repeat the operation described and effect movement of valve 16 toward open position through another increment. if, on the contrary, the clogging should be reduce. sutiioiently so that the impact or dynamic pressure in the discharge line 13 of the pump increases enough to press diaphragm 76 and rod 79' to the right as seen in FEGURE 3, so that band arm 33 will contact switch arm 65 and cause switch 57 to close, the resulting energization of solenoid 36- will move valve rod 22 and valves 23 and 24 to the right as seen in FIGURE 3 so as to cause piston ll} to be moved to the left in cylinder 37. Such piston movement will result in an incremental closing movement of valve in and lowering of rod 53 of the followup mechanism so that the arm of switch 57 w be retracted from the band arm 83 in its new poslon. A ain, the parts will remain in this position of adjustment until there is a further increase, or decrease, in the impact pressure in pump discharge pipe 13 suiiicient to initiate a valve controlling operation in the manner described.

As the dredging suction line 12 is cleared of obstruction sooner or later by the pump ll continuing to mail"- tain its suction eificiency because of water being supplied through the supplemental water bypass suction pipe 14 in addition to the dredging suction pipe, the actuator piston 4% will be moved incrementally, or in a single operation, to the left end of actuator cylinder 37 again, depending upon whether the obstruction is cleared gradually or quickly. In any event, after the piston do has thus again been moved to its extreme 1 it position arm do will have allowed lever arm 46 to drop so that the switch 57 will again be in its lowermost position. Nevertheless, the discharge impact pressure in pipe 13 will have increased sufiiciently so that the: pressure-responsive mechanism will hold the longer band arm 83 down in engage ment with switch arm 65 to keep switch closed and solenoid 36 energ The ton 465 will thus be held ed. positively in its extreme left position to maintain control valve 16 in its farthest closed position until substantifl clogging of the dredging suction line 12 occurs again.

In FEGURE 4 an alternative type of control mechanism for the piston and cylinder fluid actuator 37, as is shown. The connection of such actuator to the control valve is the same as shown in FEGURES l and 2 and need not be described further. In this control mechanism instead of the supply of compressed air to the opposite ends of cylinder 37 being controlled by a single actuator valve rnecnanism, two structurally independent valve units are used. Compressed air supply line 26 controlled by valve 27 branches and one branch is connected to the solenoid valve lilll and the other branch is connected to the solenoid valve 16ft. Valve 1% is also connected to the outlet pipe 33 and valve Si is connected to the outlet pipe 34, communicating with the left and right ends, respectively, of actuator cylinder '37. In addition, outlet pipe 33 has in it a valve 162 in series with solenoid valve tilt) and outlet pipe '34 has in it valve 19:3 in series with solenoid valve llll.

Solenoid valves res and ltll are of the normally open type and valves dill and 33-3 are one-way restricting valves which restrict, to some extent, or meter, how of compressed air from the respective solenoid valves to the actuator cylinder 37 but do not restrict flow in the opposite direction. To the solenoid valves 1% "id l-ill are connected exhaust pipes 29 and 35) respectively. Energization of these valves will cause the supply of compressed air through them to their respective outlet pipes to be shut off and the outlet pipes will be connected to their respective exhaustpipes 29 and 33?. When both valves are deenergizec, in retorc, compressed air from. pipe 26 will be supplied to both ends of the actuator cylinder 37 so that piston will not be moved. it

so leno-id valve is energized outlet pipe 33 will be con nected to exhaust pipe '2? and the branch of compressed air pipe as leading to the solenoid valve 1% will be closed. Consequently, the left end of the actuator cylinder 37 will be vented and the piston will be moved toward the left, if it is not already in its extreme left position, by compressed air supplied through solenoid valve 161 and outlet pipe 34. Conversel if solenoid valve llll is energized the supply of compressed air through its branch to the right end of cylinder 57 will be cut off and outlet pipe 34 will be connected to exhaust pipe The higher pressure in the left end of cylinder 37 will therefore force piston toward the right if it is not already in its extreme ri ht position.

The pressure-responsive mechanism includes a cylinder in which a piston is received. The conduit as connected to pump discharge pipe 13 is connected to this cylinder adjacent to one end and the cylinder has an exhaust port 96 located adiacent to its other end which may be connected to an exhaust pipe 16? if desired. Pressure exerted on the piston 19;; by air under pressure supplied by the pipe urges the piston toward the upper end of the cylinder tea as seen in FIGURE 4. Such movement of the piston is opposed by a compr on spring encircling the piston rod 1% connected to the piston 1% and to a bearin plate All ed by the spring The force exerted by such spring can be adjusted by moving along the hollow stem ill the nut plate 112 against which the other end of spring 1% bears. Piston rod 1&9 extends through such stem 111.

The bearing plate ill) carries a cam bar 113, having a central depression 114 and bosses 115 at opposite sides of the depression. Such depression is of a length substantially equal to the spacing between the switch arm lilo of switch ill? and the switch arm 118 of switch 119. Such switches are mounted on the slide 129 which is guided by rollers 121 for linear movement along a path parallel to piston rod 1%. One end of this slide carries the cross bar 122 which is positioned for engagement by the roller 59 on arm 5%? which is mounted on the end 41 of the actuator piston rod 39. Such cross bar is inclined to some extent relative to the length of slide so that lengthwise movement of such slide will be etfected by lengthwise movement of piston rod 39.

A source of power 123 has one terminal connected to each of the solenoids of valves 1% and 101 by a common lead 124, and its other terminal is connected by a lead 125 to both of the switches 117 and 119. Switch 117 is connected by a lead 126 to the solenoid of valve 101 and switch 119 is connected by a lead 127 to the solenoid of valve Switches 117 and 11% are of the normally open type and movement of their switch arms 116 and 113 toward such switches, respectively, will close such switches. Consequentl downward movement of the bar 113 will shift the switch arm 116 to close switch 117 without closing switch ll), while upward movement of such bar will eilect movement of switch arm 118 to close switch 119 without closing switch 117. The height of bosses 115 beyond the depression 114 between them is suflicient to eiiect such switch closing movement of the switch arms.

In general, the operation of the control mechanism shown in FIGURE 4 is sir ilar to the operation of the control mechanism shown in FlGURE 3 which has been described above. Assuming that the dredging suction pipe 12 is completely clear of clogging, the piston 40 will be in its extreme position to the left in FEGURE 4 to maintain the bypass valve 16 closed, or as far closed as it is capable of being moved. The arm 50 on the right end 41 of piston rod 39 will be in its farthest left position so that roller 49 engaging cross bar 122 will be holding slide 1224 in its uppermost position. The pressure in pump discharge line 13 will be high and piston 1G5 will be held in its uppermost position in cylinder illi.

Such position of the piston will cause the lower boss 115 to be in engagement with switch arm 118 for closing switch 119, even though the slide 129 is in its uppermost position. Consequently, the circuit of solenoid valve 160 will be energized. The left end of cylinder 37 will thus be vented through this solenoid valve, whereas compressed air will be supplied to the right end of cylinder 37 from the supply pipe 26 through solenoid valve 1191 and restricting valve 163.

If an obstruction now occurs in the dredging suction line 12, the pressure in the pump discharge pipe 13 will be reduced, resulting in a reduced pressure in the lower portion of cylinder 104 as communicated to it through conduit 86. Spring 108 will therefore draw the piston rod 169 and piston downward and move bar 113 downward until the lower boss 115 first releases the arm 118 of switch 119 and then the upper boss 115 will shift arm 116 of switch 117 to the right to close this switch. Opening of switch 119 has caused deenergizataion of the solenoid of valve 100 before closing of switch 117 effects energization of the solenoid of solenoid valve 181. Compressed air is therefore first admitted to the left end of cylinder 37 gradually through solenoid valve 199 and restricting valve 1&2 while the right end of cylinder 37 is vented through restricting valve 103 and solenoid valve 101. The greater pressure thus produced on the left side of piston 46 will efiect movement of such piston to the right as seen in FIGURE 4 which causes by-pass valve 16 to move toward open position.

As the piston 4-0 moves the piston rod end 41 and arm 50 to the right as seen in FIGURE 4, the slide 120 will be lowered until the switch arm 116 rides downward off the upper boss 115 of bar 113. Such switch arm movement will cause switch 117 to be opened, deenergizing the solenoid of solenoid valve 101. Compressed air will then be supplied from supply conduit 26 through both solenoid valves to the opposite ends of cylinder 37 so as to balance the pneumatic pressure on opposite sides of piston 46. The piston will therefore come to a stop and will remain in that position as long as the dynamic pressure in the pump discharge pipe 13 remains unchanged. If further clogging should occur in the dredging suction pipe 12 so as to reduce further the pressure in the pump discharge line and in the lower portion of cylinder 104, spring 108 will move piston rod 109 and bar 113 down farther so that the upper boss on this bar will move switch arm 116 to close again switch 117. Such switch closing will result in reenergization of the solenoid of solenoid valve 101 so as to vent the right end of actuator cylinder 37. The higher pressure in the left end of such cylinder will effect movement of piston 40 farther to the right as seen in FIGURE 4, thus opening bypass valve 16 through a further increment while slide 121) will move downward farther until switch arm 116 again rides off the upper boss 115 of bar 113. The parts will then remain in this new position of equilibrium until a further substantial change in the dynamic pressure in the discharge pipe 13 of pump 11.

When the obstruction in the dredging suction pipe 12 begins to clear so that the dynamic pressure in the pump discharge line rises, the pressure in the lower end of cylinder 164 will be increased correspondingly to raise piston 105 and rod 109 against the opposition of compression spring 168. As bar 113 is thus raised switch arm 118 will be moved to close switch 119 for energizing the solenoid of solenoid valve 100. Such valve energizati o-n will vent the left end of cylinder 37 so that the air under higher pressure in its right end will move piston 41? to the left which will effect incremental closing movement of bypass valve 16. At the same time, movement of arm Silto the left will move slide 120 upward so that switch arm 11% will move off the lower boss 115 of the cam bar 113 to enable switch 119 to open and 'deenergize solenoid valve 100. Both ends of cylinder 37 then will receive pneumatic pressure from pipe 26 which will act on opposite sides is of piston 49. The valve 16 will remain in this new position until more of the obstruction in the dredging suction pipe 12 is cleared, or the obstruction in the dredging suction pipe again increases, thereby producing a substantial charge, either increase or decrease, in the dynamic pressure in the discharge pipe 13 which will initiate a further incremental control movement of the mechanism described and a corresponding incremental closing or opening movement of the bypass control valve 16.

I claim as my invention:

1. A relief valve system comprising a pump having an inlet and an outlet, a suction pipe leading to said inlet, a discharge pipe leading from said outlet, a normally closed relief valve for delivery of water to said system, a first cylinder, a piston therein, a connecting rod for said piston, an operative connection between said connecting rod and said relief valve, the relief valve being movable from closed toward open position in response to movement of the connecting rod in a first direction and from open toward closed position in response to movement of said connecting rod in a second direction, a second cylinder, an inlet pipe connection for fluid under pressure leading to said second cylinder, first and second exhaust means leading from said second cylinder, first and second pipe connections leading from said second cylinder to end portions, respectively, of said first cylinder at opposite ends of said piston, a valve stem slidably mounted in said second cylinder, first and second longitudinally spaced valve elements on said valve stem, a first solenoid operable when energized to actuate said valve stem to and retain it in a position situating said first and second valve elements at locations to afford communication between said inlet pipe connection and said first pipe connection and between said second pipe connection and said second exhaust means and shut off communication between the inlet pipe connection and the second pipe connection and between the first pipe connection and the first exhaust means, a second solenoid operable when energized to actuate the valve stem to and retain it in position situating the first and second valve elements at locations to afford communication between said inlet pipe connection and said second pipe connection and between said first pipe connection and said first exhaust means and shut off communication between the inlet pipe connection and the first pipe connection and between the second pipe connection and the second exhaust means, when said first and second solenoids are deenergized, said valve stem being movable to a mid-position in said second cylinder situating said first and second valve elements at locations shutting off communication between the inlet pipe conection and all of said first and second pipe connections and exhaust means, as Well as between the first and second pipe connections and the first and second exhaust means, a movably mounted member, first and second normally open electric switches fixedly supported on said movably mounted member, first and second means independently actuable to cause said first and second switches, respectively, to be closed, a first circuit including said first solenoid and said second switch, a second circuit including said second solenoid and said first switch, a lever, a diaphragm, an operative connection between said diaphragm and said lever, a conduit leading from said discharge pipe to said diaphragm, discharge pressure in said system acting through the instruimen-tali-v ty of the diaphragm and said operative connections to retain said lever pressed against said first means and the first means in position maintaining said first switch closed when discharge pressure above a predetermined low discharge pressure is existent in the system, resilient means operable to release said lever from said first means and cause it to be moved into pressingly engaged relation with said second means to retain the second means in position maintaining said second switch closed when discharge pressure in said system becomes reduced to said predetermined low discharge pressure, the movably mounted member with said first and second electric switches as a unit being actuable in a direction causing said second means to be moved away from said lever and said first means to be moved toward said lever in response to movement of said connecting rod in said first direction and in direction causing the second means to be moved toward said lever and the first means to be moved away from the lever in response to movement of the connecting rod in said second direction, fluid under pressure in said inlet ipe connection and said first cylinder being operable while said first solenoid is energized to move said relief valve to an open position dependent upon and inversely proportional to discharge pressure at the time existent in said system and to cause said second means to be released from said lever when the relief valve reaches said mentioned open position thus to cause the first solenoid to be deenergized, fluid under pressure trapped in the first cylinder at the opposite ends of said piston therein being operable upon deenergization of the first solenoid to retain said relief valve in said mentioned open position, and fluid under pressure in said inlet pipe and the first cylinder being operable while said second solenoid is energized to move said relief valve to and retain it in closed position.

2. In a dredge, suction dredging mechanism comprising a dredging pump having an intake and a discharge pipe, a dredging suction pipe connected to said pump intake and having its intake end submerged in a body of water below said dredging pump and in excavating relationship to the bottom of such water body, a supplemental water supply suction pipe bypassing the suction end portion of said dredging suction pipe, connected to said dredging suction pipe adjacent to said pump intake and having its intake end also submerged below said dredging pump in the same body of water but above the bottom thereof, a bypass control valve in said supplemental water supply suction pipe movable to alter the effective passage therethrough, a cylinder, a piston in said cylinder connected to said bypass control valve to eifect opening and closing movement thereof in response to movement of said piston in said cylinder in opposite directions, respectively, fluid supply means connected to opposite ends of said cylinder for supplying fluid under pressure thereto, electrically operated regulating valve means operatively connected to said pressure fluid supply means, operable to effect supply of fluid under pressure to one end or the other end of sadi cylinder selectively, a movably mounted member, first and second normally open electric switches supported on said movably mounted member, connected to said electrically operated regulating valve means and operable to efliect movement of such valve means in one direction by closing of said first switch and in the opposite direction by closing of said second switch, pressure responsive means movable in response to changes in pressure in said discharge pipe and operatively engageable with said first switch and said second switch to effect closing of said first switch by relative movement of said pressure responsive means and said movably mounted member in one direction and to eifect closing of said second switch by relative movement of said pressure responsive means and said movably mounted member in the opposite direction, and means operatively connecting said movably mounted member and said piston enabling movement of said piston to effect movement of said movably mounted member relative to said pressure responsive means in a direction tending to open that switch closing of which effected such piston movement.

3. In a dredge, hydraulic dredge production sustaining control mechanism, comprising a dredging pump, a dredging suction pipe connected to the intake of said pump and having its intake end submerged in a body of water below said dredging pump and in excavating relationship to the bottom of such water body, a supplemental water supply suction pipe bypassing the suction end portion of said dredging suction pip-e, connected to the intake of said pump and having its intake end also submerged below said dredging pump in the same body of water but above the bottom thereof, a bypass control valve regulating the effective size of passage through which supplemental water flows to said p ump through said supplemental water supply suction pipe, an actuator operatively connected to said control valve, energizing means responsive to the discharge from said pump and operatively connected to energize said actuator to vary the position of said control valve in response to variations in discharge ot said pump, and follow-up means operatively connected to said actuator and to said energizing means and operated by predetermined movement of said actuator to operate said energizing means for terminating movement of said actuator and of said control valve.

4. in a dredge, hydraulic dredge production sustaining control mechanism, comprising a dredging pump, a dre ging suction pipe connected to the intake of said pump and having its intake end submerged in a body of water below said dredging pump and in excavating relationship to the bottom of such water body, a supplemental water supply suction pipe bypassing the suction end portion of said dredging suction pipe, connected to the intake of said pump and having its intake end also submerged below said dredging pump in the same body of water but above the bottom thereof, a bypass control valve regulating the eftective size of passage through which supplemental water flows to said pump through said supplemental water supply suction pipe, a fluid-pressure-operated actuator operatively connected to said control valve, valve means operatively connected to said actuator and operable to control flow of operating fluid therefor, energizing means responsive to the discharge from said pump and operatively connected to operate said valve means for effecting transitory how of fluid for said actuator to effect incremental movement of said actuator to shift said control valve for regulating correspondingly the flow of water through said supplemental water supply suction pipe to said pump in response to a predetermined variation in the pump discharge, and follow-up means operatively connected to said actuator and to said valve means and operated by such incremental movement of said actuator to move said valve means for interrupting such flow of fluid for said actuator and thereby terminate movement of said actuator and of said control valve.

5. In hydraulic dredge production sustaining control mechanism for a control valve movable by an actuator to regulate the flow of water through a supplemental water supply suction pipe connected to the intake of the dredging pump, bypassing the suction end portion of the dredging suction pipe also connected to the dredging pump intake and having its intake end submerged below the dredging pump in the same body of water as that in which the intake end of the dredging suction pipe is submerged, the improvement which comprises a linearly reciprocable member, two spaced switches mounted on said reciprocable member, operatively connected to the control valve actuator and energizable to eifect movement of such actuator in opposite directions, respectively, in response to opposite changes in the discharge from the dredging pump, to vary correspondingly the position of the control valve, a contact member responsive to the discharge from the dredging pump selectively engageable with said switches, respectively, depending upon the change in the discharge from the dredging pump and means operatively connecting said reciprocable member to the control valve actuator and operable, in response to movement of the control valve actuator, to effect reciprocation of said reciprocable member in a direction for withdrawing said contact member from the switch with which it was engaged, to deenergize said electrical energizing means while the discharge from the dredging pump remains substantially constant and to terminate movement of the control valve actuator and of the control valve.

13 6. In a dredge, hydraulic dredge production sustaining control mechanism, comprising a dredging pump, a dredging suction pipe connected to the intake of said pump and having its intake end submerged in a body of water below said dredging pump and in excavating relationship to the bottom of such water body, a supplemental water supply suction pipe bypassing the suction end portion of said dredging suction pipe, connected to the intake of said pump and having its intake end also submerged below said dredging pump in the same body of water but above the bottom thereof, a bypass control valve regulating the effective size of passage through which supplemental water flows to said pump through said supplemental Water supply suction pipe, a fluid-pressure-operated actuator operatively connected to said control valve, a source of fluid under pressure, supply valve means operatively connected to said source of fluid under pressure and to said actuator and operable to control supply of fluid under pressure to said actuator, energizing means responsive to the discharge from said pump and operatively connected to operate said supply valve means for effecting transitory supply of fluid under pressure to said actuator to efifect incremental movement of said actuator to shift said control valve for regulating correspondingly the flow of Water through said supplemental water supply suction pipe to said pump in response to a predetermined variation in the pump discharge, and follow-up means operatively connected to said actuator and to said supply valve means and operated by such incremental movement of said actuator to move said supply valve means for interrupting such supply of fluid under pressure to said actuator and thereby terminate movement of said actuator and of said control valve.

7. The control mechanism defined in claim 6, and solenoid means operatively connected to the valve means and energizable to effect fiow-contro1ling movement thereof, and the follow-up means including switch means interposed between the dredging pump discharge responsive means and said solenoid means and shiftable by movement of the actuator to deenergize the solenoid means as a result of being shifted a predetermined amount by the actuator.

8. The control mechanism defined in claim 7, in which the switch means includes two spaced switches in circuit with the solenoid means, a slide carrying said switches and shiftable by movement of the actuator, and a switchactuating member connected to and movable by the dredging discharge responsive means for effecting closing of one of said switches by movement of such member relative thereto and opening of such switch by shifting of said slide relative to said switch actuating member effected by movement of the actuator.

9. The control mechanism defined in claim 8, and adjusting means operatively connected to the switch-actuating member movable by the dredging pump discharge responsive means for varying the initial position of the switch-actuating member relative to the switches.

References Cited in the file of this patent UNITED STATES PATENTS 

2. IN A DREDGE, SUCTION DREDGING MECHANISM COMPRISING A DREDGING PUMP HAVING AN INTAKE AND A DISCHARGE PIPE, A DREDGING SUCTION PIPE CONNECTED TO SAID PUMP INTAKE AND HAVING ITS INTAKE END SUBMERGED IN A BODY OF WATER BELOW SAID DREDGING PUMP AND IN EXCAVATING RELATIONSHIP TO THE BOTTOM OF SUCH WATER BODY, A SUPPLEMENTAL WATER SUPPLY SUCTION PIPE BYPASSING THE SUCTION END PORTION OF SAID DREDGING SUCTION PIPE, CONNECTED TO SAID DREDGING SUCTION PIPE ADJACENT TO SAID PUMP INTAKE AND HAVING ITS INTAKE END ALSO SUBMERGED BELOW SAID DREDGING PUMP IN THE SAME BODY OF WATER BUT ABOVE THE BOTTOM THEREOF, A BYPASS CONTROL VALVE IN SAID SUPPLEMENTAL WATER SUPPLY SUCTION PIPE MOVABLE TO ALTER THE EFFECTIVE PASSAGE THERETHROUGH, A CYLINDER, A PISTON IN SAID CYLINDER CONNECTED TO SAID BYPASS CONTROL VALVE TO EFFECT OPENING AND CLOSING MOVEMENT THEREOF IN RESPONSE TO MOVEMENT OF SAID PISTON IN SAID CYLINDER IN OPPOSITE DIRECTIONS, RESPECTIVELY, FLUID SUPPLY MEANS CONNECTED TO OPPOSITE ENDS OF SAID CYLINDER FOR SUPPLYING FLUID UNDER PRESSURE THERETO, ELECTRICALLY OPERATED REGULATING VALVE MEANS OPERATIVELY CONNECTED TO SAID PRESSURE FLUID SUPPLY MEANS, OPERABLE TO EFFECT SUPPLY OF FLUID UNDER PRESSURE TO ONE END OR THE OTHER END OF SAID CYLINDER SELECTIVELY, A MOVABLY MOUNTED MEMBER, FIRST AND SECOND NORMALLY OPEN ELECTRIC SWITCHES SUPPORTED ON SAID MOVABLY MOUNTED MEMBER, CONNECTED TO SAID ELECTRICALLY OPERATED REGULATING VALVE MEANS AND OPERABLE TO EFFECT MOVEMENT OF SUCH VALVE MEANS IN ONE DIRECTION BY CLOSING OF SAID FIRST SWITCH AND IN THE OPPOSITE DIRECTION BY CLOSING OF SAID SECOND SWITCH, PRESSURE RESPONSIVE MEANS MOVABLE IN RESPONSE TO CHANGES IN PRESSURE IN SAID DISCHARGE PIPE AND OPERATIVELY ENGAGEABLE WITH SAID FIRST SWITCH AND SAID SECOND SWITCH TO EFFECT CLOSING OF SAID FIRST SWITCH BY RELATIVE MOVEMENT OF SAID PRESSURE RESPONSIVE MEANS AND SAID MOVABLY MOUNTED MEMBER IN ONE DIRECTION AND TO EFFECT CLOSING OF SAID SECOND SWITCH BY RELATIVE MOVEMENT OF SAID PRESSURE RESPONSIVE MEANS AND SAID MOVABLY MOUNTED MEMBER IN THE OPPOSITE DIRECTION, AND MEANS OPERATIVELY CONNECTING SAID MOVABLY MOUNTED MEMBER AND SAID PISTON ENABLING MOVEMENT OF SAID PISTON TO EFFECT MOVEMENT OF SAID MOVABLY MOUNTED MEMBER RELATIVE TO SAID PRESSURE RESPONSIVE MEANS IN A DIRECTION TENDING TO OPEN THAT SWITCH CLOSING OF WHICH EFFECTED SUCH PISTON MOVEMENT. 